Audio codec

(1) (audio enCOder/DECoder) Software that compresses and decompresses a digital audio signal. MP3, Windows Media Audio (WMA), Dolby Digital and DTS are examples of popular codecs that compress and decompress digital audio. The audio codec may also be a hardware circuit. See codec examples, codec, Windows Media formats, QuickTime, audio compression, perceptual audio coding and G. standards.

(2) (audio enCOder/DECoder) A hardware circuit that converts sound waves into PCM digital code and vice versa. The term may refer to only the A/D and D/A conversion, or it may include the compression technique for further reducing the signal (definition #1 above). If the codec is specialized for human voice, it is known as a "speech codec," "voice codec" or "vocoder" (see speech codec). See sampling and codec.

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The term audio codec has two meanings, both referring to something that encodes and decodes. The term codec is a combination of 'coder-decoder'.

In software, a codec is a computer program that compresses/decompresses digital audio data according to a given audio file format or streaming audio format. The object of a codec algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality. This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most codecs are implemented as libraries which interface to one or more multimedia players, such as QuickTime Player, XMMS, Winamp, VLC media player, MPlayer or Windows Media Player.

In hardware, the term "audio codec" refers to a single device that encodes analog audio as digital signals and vice versa. This is used in sound cards that support both audio in and out, for instance.

See also

• Audio compression (data)
• Codec
• Digital signal processing
• List of codecs
• Open source codecs and containers
• Comparison of audio codecs

v • d • e Data compression methods Lossless Theory Entropy · Complexity · Redundancy · Lossy Entropy encoding Shannon-Fano · Shannon–Fano–Elias · Huffman · Adaptive Huffman · Arithmetic · Range · Golomb · Exp-Golomb · Universal (Elias · Fibonacci) Dictionary RLE · Byte pair encoding · DEFLATE · Lempel–Ziv (LZ77/78 · LZSS · LZW · LZWL · LZO · LZMA · LZX · LZRW · LZJB · LZT · ROLZ) Others CTW · BWT · PPM · DMC Audio Theory Companding · Convolution · Dynamic range · Latency · Sampling · Nyquist–Shannon theorem · Sound quality Audio codec parts LPC (LAR · LSP) · WLPC · CELP · ACELP · A-law · μ-law · ADPCM · DPCM · MDCT · Fourier transform · Psychoacoustic model Others Bit rate (CBR · ABR · VBR) · Speech compression · Sub-band coding Image Terms Color space · Pixel · Chroma subsampling · Compression artifact · Image resolution Methods RLE · Fractal · Wavelet · EZW · SPIHT · LP · DCT · Chain code · KLT Others Test images · PSNR quality measure · Quantization Video Terms Video Characteristics · Frame · Frame rate · Interlace · Frame types · Video quality · Video resolution Video codec parts Motion compensation · DCT · Quantization Others Video codecs · Rate distortion theory · Bit rate (CBR · ABR · VBR) Timeline of information theory, data compression, and error-correcting codes See Compression formats for formats and Compression software implementations for codecs

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